1. Biofertilizers Agriculture Microbiology

2. Introduction Biofertilizers are the biological substances that can enhance plant nutrition by mobilizing or increasing nutrient availability in the soil. The main source of biofertilizers are bacteria, fungi and cyanobacteria.

3. Introduction

4. Production process of biofertilizers

6. Biofertilizers vs Chemical fertilizers CharacteristicsBiofertilizerChemical Fertilizer DefinitionBiofertilizers are the biological substances that can enhance plant nutrition by mobilizing or increasing nutrient availability in the soil. Chemical fertilizers are chemical-based substances consisting of one or more nutrients required for the enhancement of plant growth and soil fertility. CompositionComposed of natural materials that are extracted from animals and plants. composed of non-organic and artificially cultivated elements. NPK Ratio – Nitrogen Phosphorus Potassium Ratio Very Low.High. Shelf-LifeShorter shelf life.Longer shelf life. Soil LifeMakes the soil healthier and more fertile.Soil life will not be enriched or stimulated. ExamplesRhizobium, Azotobacter, Azospirilium and blue green algae (BGA) (NH₄)₂SO₄, NH₄NO₃, CO(NH₂)₂ & NH4Cl.

7. Why are biofertilizers preferred over chemical fertilizers? 1.Less harmful then Chemical fertilizers. 2.They contain organic materials while chemical fertilizers are made up of harmful chemicals. 3.Production process is less difficult then chemical fertilizers. 4.It Supports the growth of nitrogen-fixing bacteria where chemical fertilizer destroys the growth of nitrogen-fixing bacteria as it contains high acid content. 5.More biodegradable, sustainable, and environmentally friendly then Chemical fertilizers. 6.Biofertilizers ensure an airy soil structure, where chemical fertilizers lead to soil acidification. 7.Overuse of chemical fertilizer causes soil pollution, where biofertilizer increases soil fertilization. 8.Biofertilizer provides almost all nutrients but chemical fertilizer supply only one specific nutrient. 9.Production & manufacture cost is lower than chemical fertilizer.

8. Biofertilizer preparation Criteria for strain selection of biofertilizers 1.Should usually be a nitrogen fixer. 2.Should be harmless for crops and human. 3.Should be capable to provide nutrients from soil to plants. 4.Should be able to multiply to compete with infectious microbes. 5.Should be able to survive in hostile env. in soil. 6.Should always be available for biofertilizer production. 7. Should increase crop yields. Rhizobium, Azotobacter, Azospirillum, and blue-green algae (BGA) are biofertilizers.

9. The carrier is a medium that can carry the microorganisms in sufficient quantities and keep them viable under specified conditions in biofertilizer. The most frequently used carrier for inoculant production is peat. A wide range of substitutes e.g. lignite, coal, charcoal, bagasse, filter mud, vermiculite, polyacrylamide, mineral soils, vegetable oils, etc. have been tested as alternative carriers.

10. Quality control measures for Inoculants Like every product, the bio-fertilizers should also follow certain standards. 1.Inoculant should be carrier based or liquid based. 2.The carrier material should be in the form of powder, i.e. peat, lignite, peat soil, and humus, etc. 3.The inoculant should contain minimum of 10 ₈ viable cells of bioinoculant/g of carrier on dry weight basis when it is stored at 25–30°C. 4.The inoculant should have a maximum expiry period of 12 months from date of manufacture. 5.The pH of inoculant should be between 6.0 and 7.5. 6.Inoculant should be packed in 50–75 microns low-density polythene bags. 7.It should be free from any contaminant/contamination with other microorganisms. 8.Each packet containing the biofertilizer should be marked with the information’s e.g., name of product, date of manufacture & expiry, net quantity and storage instructions.

11. Green Manuring Two main methods of inoculation are currently being used (a) seed inoculation and (b) soil inoculation. Green manuring is defined as a “farming practice where a green manure crop in the cropping system is used for building soil organic matter and soil structure.” Some of the cultivated legumes and annual legumes such as Crotolaria juncea, C. striata, Cassia mimosoides, Cyamopsis pamas, Glycine wightii, Indigofera linifolia, Sesbania rostrata, Leucaena leucocephala, etc. contribute nitrogen. These are green legume plants. Functions: 1.They improve soil nutrients and protect soil erosion. 2.They fix nitrogen in soil, thus Less chemical fertilizers are required. 3.Minimize the pathogenic organisms in soil 4.Green manures provide forage for pollinating insects. 5.Cause reclamation of “usar lands”.

12. Role of cyanobacteria as biofertilizer,

13. A mixture of 5 or 6 regionally acclimatized strains of cyanobacteria e.g. species of Anabaena, Aulosira, Cylindrospermum, Gloeotrichia, Nostoc, Plectonema, Tolypothrix etc. are generally used as starter inoculum.

14. Mass Cultivation of Azolla

15. The aquatic heterosporus fern contains endo­phytic cyanobacterium, Anabaena azollae in its leaf cavity. There are number of species of Azolla, namely A. caroliniana, A, filiculoides, A. maxicana, A. nilotica, A. pinnata and A. rubra which are used as biofertilizer especially for paddy. There are two methods for its application in field: (a) Incorporation of Azolla in soil prior to rice cultivation, and (b) Transplantation of rice followed by water draining and incorporation of Azolla. Azolla mat is harvested and dried to use as green manure.

16. Endophytic Nitrogen Fixers The term endophyte refers to the microorganisms (bacteria and fungi) that colonize root interior of plants and live most of their life inside the plant tissue. Examples are Fusarium oxysporum, Bradyrhizobium japonicum, Fusarium culmorum & Fusarium venenatum etc. (i)Facultative Endophytic Diazotrophs: Azospirillum spp., A. lipoferum & A. brasilense. (ii) Obligate Endophytic Diazotrophs: Acetobacter diazotrophicus (syn. Gluconacetobacter diazotrophicus)-a nitrogen fixing bacterium, alpha sub-class of the proteobacteria. Azoarcus spp., Herbaspirillum spp. and a partially identified Burkholderia sp.-beta sub- class of the proteobacteria. (iii) Other Bacteria: 1.Alcaligens-isolated from the rhizosphere of wet rice land. 2.Burkholderia-have potential as rice inoculant.

17. Isolation and Identification of Endophytes Sample plant In petri plates with selected media

18. Bio-Fertilizers aiding Phosphorus Nutrition There are some fungi such as Aspergillus awamori, Penicillium digitatum, etc. and bacteria like Bacillus polymyxa, Pseudomonas striata, etc. that solubilize unavailable form of P to available form. Vesicular-arbuscular mycorrhizal (VAM) fungi colonize roots of several crop plants. These are obligate symbionts and cannot be cultured on synthetic media. They help plant growth through improved phosphorus nutrition and protect the roots against pathogens.

19. Ectomycorrhizal Fungi Ectomycorrhizal Fungi: In this case, 1.The basidiospores, chopped sporocarps, sclerotia, pure mycelial culture, fragmented mycorrhizal roots or soil from mycorhizosphere region can be used as inoculum. 2.The inoculum is mixed with nursery soil and seeds are sown thereafter.

20. The host plants which support large scale production of inoculum are sudan grass, strawberry, sorghum, maize, onion, citrus, etc. There are two methods of using the inoculum: (a) Using a dried spore-root-soil to plants by placing the inoculum several centimeters below the seeds or seedlings (b) Using a mixture of soil- roots, and spores in soil pellets and spores are adhered to seed surface with adhesive. The starter inoculum of VAM can be isolated from soil by wet sieving and decantation technique VA Mycorrhizal Fungi

21. Disadvantages of bio & chemical fertilizers The disadvantages of biofertilizers 1.Biofertilizers provide lower nutrient density than chemical fertilizers, so more product is often required for the same effect 2.Biofertilizer production requires specific machinery 3.Biofertilizers can be difficult to store and may have a much shorter shelf-life than chemical fertilizers 4.Biofertilizers are often plant specific; what works on one crop does not work on another 5.Biofertilizers can have a strong, distinctive odor. Disadvantages of chemical fertilizers 1.They are expensive. 2.Chemical fertilizers can deplete the soil. 3.They pollute the environment. 4.Chemical fertilizers interrupt soil ecology. 5.Their application can result in weak plants. 6.Contains limited nutrients. 7.Causes Over-fertilization or PH balance troubles. 8.They provide only short term benefits.

22. why we use nitrogen fixing microorganisms as potential inoculate for Biofertilizer production Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas finto “fixed nitrogen” compounds, such as ammonia etc. 1.supply plants with the vital nutrient that they cannot obtain from the air themselves. 2.They usually do not allow pathogens to flourish. 3. protect the environment from pollutants since they are natural fertilizers. 4.Eco-friendly, more available and cost-effective. 5. capable of transforming atmospheric nitrogen into fixed nitrogen (inorganic compounds usable by plants). 6. play an important role in the nitrogen cycle. 7.They can form symbiotic relationships with members of all major plant groups. 8.When applied as green manure, it promotes soil fertility. 9.Crop waste can be utilised to help with weed control. 10.Nitrogen-fixing bacteria examples comprise Rhizobium (formerly Agrobacterium), Frankia, Azospirillum, Azoarcus, Herbaspirillum, Cyanobacteria, Rhodobacter, Klebsiella, etc. 11.helps in fixing nitrogen in leguminous plants. 12.growth hormone production, phosphate solubilization, plant disease management and reclamation of better soil health. Species of Azotobacter, Bacillus, Clostridium, and Klebsiella etc.

23. why we use nitrogen fixing microorganisms as potential inoculate for Biofertilizer production Nitrogen-fixing bacteria. Genus Rhizobium and Bradyrhizobium.

24. Biofertilizers